The dopaminergic stabilizer pridopidine is to a major extent N-depropylated by CYP2D6 in humans

Abstract

The influence of the cytochrome P450 enzyme CYP2D6 in the metabolism of the novel dopaminergic stabilizer pridopidine was investigated in healthy Swedish Caucasians. Six extensive metabolizers (EM) and six poor metabolizers (PM) of debrisoquine were given a single oral dose of pridopidine (EM, 50 mg; PM, 25 mg). The mean total plasma clearance of pridopidine was 541 and 138 mL/min in EM and PM, respectively (p = 0.003), and was slightly higher in PM than the mean renal plasma clearance (105 mL/min; p = 0.11). The mean plasma area under the time-concentration curve between time zero and 32 h (AUC(0-32 h)) of the N-depropyl metabolite ACR30 was higher in EM than in PM (1,377 vs. 61 nmol h/mL, respectively; p < 0.001). The urinary excretion of pridopidine + ACR30 was high in both EM (85 %) and PM (78 %). The dose-adjusted peak concentration (C(max)) was not statistically different in EM and PM; consequently, the oral absorption of pridopidine was close to complete. Following a single dose of pridopidine, the drug is N-depropylated by CYP2D6 in EM, while in PM the most important elimination pathway is renal glomerular filtration. Results of studies examining the effects of multiple repeat dosing suggest that the CYP2D6 enzyme is at least partly inactivated by pridopidine.